Recently, as interest in environment and human health has gradually increased, there has been increased consumption of antimicrobial-treated products, including baby and children's products and utensils, such as chopping boards, food storage containers or scrubbers, which were treated with antimicrobial agents to inhibit the multiplication of bacteria or fungi. This antimicrobial treatment has been applied to a wide range of products, including daily-use articles, household appliances or building materials.
As the demand for such products treated with antimicrobial agents has increased, a variety of highly functional antimicrobial compositions have been developed. With respect to patent documents that disclose such antimicrobial compositions, Korean Patent Registration No. 0606253 discloses a disinfectant/antimicrobial and deodorant aqueous composition for fabric deodorizers, which comprises, as active ingredients, nano silver ions supported on an inorganic material such as calcium oxide, silica, alumina or zeolite, a persimmon extract, perfume, a surfactant and ethanol. This composition has disinfectant/antimicrobial functions together with deodorizing functions and is intended for use in fabric deodorizers.
Korean Patent Laid-Open Publication No. 2007-0119219 discloses a coating composition for antimicrobial and deodorizing applications, which contains, based on 100 parts by weight of an inorganic binder, 5-40 parts by weight of a functional spherical silica having silver nanoparticles supported thereon, the spherical silica having a mean particle diameter of 2-5 μm. This composition is an antimicrobial composition intended for use in printers or copiers and has limited applications.
Particularly in the case of, for example, paints, antimicrobial paints comprising an antimicrobial agent containing silver nanoparticles are coming into the market. However, in the case of such antimicrobial paints, the silver nanoparticles are oxidized by the solvent contained in the paint composition, thus making it difficult to effectively exhibit the antimicrobial activity of the antimicrobial agent. If the antimicrobial agent is added in large amounts in order to overcome this problem associated with the oxidation of silver nanoparticles, the silver nanoparticles will be likely to agglomerate, and the coating film formed of the paint composition can be discolored due to the increase in the content of the metal component. In addition, the coating film will be thicker, and thus be easily peeled off.
For these reasons, there have been developed and used antimicrobial agents comprising silica carriers which contain silver nanoparticles in their fine pores as disclosed in the above-mentioned patents in order to increase the dispersibility of the silver nanoparticles. However, because the silica carriers are spherical in shape, the agglomeration of the silver nanoparticles still occurs, and the dispersibility of the silver nanoparticles is low such that the microbial agents have insufficient antimicrobial activity.